The term "uncanny valley" was coined by Japanese robotics professor Masahiro Mori in 1970. Basically it describes our emotional reaction to robots; when they look different to us, think WALL•E, we react "cute," but when robots approach a humanoid form we can find them creepy and repulsive (i.e. uncanny). For us to warm to humanoid robots their design must cross the uncanny valley and become so similar to us that we are no longer grossed out, think the robot boy David in the movie A.I.
However, crossing this valley is very hard since we're highly trained to notice almost imperceptible nuances in human behavior. This humanoid robot, called ECCE, I think we'd all agree is right in the uncanny valley - skin would help!